1. Field of the Invention
The present invention relates to a seat for a vehicle, and more particularly to a seat for a vehicle for protecting a seated occupant of the vehicle from the impact occurring at the time of a rear collision of the vehicle.
2. Description of the Related Art
Conventionally, among seats for vehicles such as automobiles, there has been known a seat for a vehicle for protecting a seated occupant of the vehicle from an impact occurring at the time of a rear collision of the vehicle, and one example thereof is disclosed in Japanese Patent Application Laid-Open (JP-A) No. 7-132767.
As shown in FIG. 13, this seat 100 for a vehicle is arranged such that a strip-shaped wavelike reinforcing rib section 108 is formed at a lower end portion of a seat back frame 102 in such a manner as to extend along an inner surface of a supporting bracket 104 and zigzag toward a pivotally supporting portion 106 of the seat back frame 102 in an orthogonal direction to the axial direction of the pivotally supporting portion 106. Each bent portion of the reinforcing rib section 108 close to the supporting bracket 104 is attached to the inner surface of the supporting bracket 104. As a result, when the vehicle is hit by another vehicle or the like from the rear of the vehicle (namely, during a rear collision of the vehicle), and an impact is applied to the seat 100 in the direction going from the front of the vehicle towards the rear (in the direction of arrow W in FIG. 13), a zigzag portion 108A of the reinforcing rib section 108 undergoes contracting deformation by following the buckling deformation of the supporting bracket 104, so as to absorb the impact which cannot be borne by the rigidity of the reinforcing rib section 108.
However, with this seat 100 for a vehicle, if an impact of a predetermined value or greater is applied during the rear collision, the zigzag portion 108A of the reinforcing rib section 108 undergoes contracting deformation by following the buckling deformation of the supporting bracket 104, thereby inclining a seat back 100A backwardly.